Peroxygen bleach-containing compositions have been extensively described in laundry applications as laundry detergents, laundry additives or even laundry pretreaters.
Indeed, it is known to use such peroxygen bleach-containing compositions in laundry treatment applications to boost the removal of encrustated stains/soils which are otherwise particularly difficult to remove, such as grease, coffee, tea, grass, mud/clay-containing soils and the like. However, we have found that a drawback associated with such peroxygen bleach-containing compositions is that the compositions may damage fabrics resulting in tensile strength loss and/or color damage, especially when used in a pretreatment application, i.e., when applied directly (neat) onto the fabrics, and left to act onto the fabrics for prolonged periods of time before washing the fabrics.
It is thus an object of the present invention to provide improved fabric safety and/or color safety to fabrics upon bleaching, especially in pretreatment applications where the compositions are left neat into contact with the fabrics for prolonged periods of time before washing.
Indeed, when bleaching fabrics with a composition comprising a peroxygen bleach like hydrogen peroxide, it has been found that the presence of metal ions such as copper and/or iron and/or manganese and/or chromium on the surface of the fabrics and/or the exposure to UV radiation from sunlight of the fabrics after having been contacted with the peroxygen bleach-containing composition, produces fabric damage resulting in loss of tensile strength of the fabric fibres and/or in color damage of the fabrics. Indeed, it is speculated that the presence of metal ions such as copper and/or iron and/or manganese and/or chromium on the surface of the fabrics, especially on cellulosic fibres, and/or the exposure of the fabrics to UV radiation from sunlight catalyse the radical decomposition of peroxygen bleaches like hydrogen peroxide. Thus, it is believed that a radical reaction occurs on the surface of the fabrics with generation of free radicals, which results in tensile strength loss. Furthermore, it is speculated that this generation of free radicals may further provide an aggressive decomposition of certain dyes present in the fabrics resulting thereby in chemical damage of dye molecules which is visible as discoloration and/or hue change. Dyes commonly present in colored fabrics include metal containing dyes like copper-formazan dyes or metal-azo dyes.
It has now been found that improved fabric safety and/or color safety can be achieved by formulating a liquid bleaching composition comprising a peroxygen bleach, propyl gallate and an antioxidant. More particularly, it has been found that the use, in a peroxygen bleach-containing composition for bleaching fabric, of an antioxidant together with propyl gallate, considerably reduces the color damage and/or fabric damage on a fabric bleached with such a composition, especially in a pretreatment application.
An advantage of the present invention is that excellent laundry performance on a broad range of stains and soils such as bleachable stains and/or greasy stains is also provided.
Another advantage of the present invention is that the compositions according to the present invention provide excellent performance when used in any laundry applications, for instance when used as a laundry detergent or a laundry additive, and especially when used as a laundry pretreater, or even in other applications like in hard surface cleaning applications.
Yet another advantage is that the compositions herein are physically and chemically stable upon prolonged periods of storage.
EP-B-209 228 discloses compositions comprising a peroxide source like hydrogen peroxide, metal chelating agents such as amino polyphosphonate chelants and free radical scavengers at a level of from 0.005% to 0.04% by weight of the total composition. No propyl gallate is disclosed.
European patent application number 95870082.5 discloses a peroxygen bleach-containing composition comprising two types of radical scavengers and optionally a chelating agent. No antioxidants are disclosed.
European patent application number 95870079.1 discloses a peroxygen bleach-containing compositions comprising a polyamine, and optionally a chelating agent and a radical scavenger. No antioxidants are disclosed.
In none of these patent applications it is mentioned nor suggested that the use of an antioxidant together with propyl gallate, in a peroxygen bleach-containing composition, reduce the loss of tensile strength in fabrics and/or color damage of said fabrics, when said fabrics are bleached with said composition.